Answer to Question 1
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Answer to Question 2
In space, HST can focus on infrared and ultraviolet waves invisible to ground-based observers. With no air, the seeing for Hubble is always perfect and images are much sharper than when viewed through our turbulent blanket of air, even with the best adaptive optics. As the Hubble orbits the Earth, it can be turned to view anything in the sky and not be limited by the local horizon.